Truncate product description when used as meta description

Fixes #2396

Conflicts:
	core/spec/helpers/base_helper_spec.rb
Correct MailMethod usage in mail_interceptor, order mailer and shipment mailer specs
Fix jirafe admin settings styling

Fixes #2733
Price#display_amount should return a string representation of a Spree::Money object
Order#display_total should return a string representation of a Money object
Move currnet_currency and ip_address helpers to ControllerHelpers::Order, where they're required